var year = prompt("请输入年份：");
var month = prompt("请输入月份：");

year = Number(year);
month = Number(month);


//1980年有多少天
//365  366
function runNian(year) {
    if (year % 400 === 0 || (year % 4 === 0 && year % 100 != 0)) {
        return true;
    }
    else {
        return false;
    }
}
var days = 0;


//1980年全年  +到 2018年全年
for (var i = 1980; i < year; i++) {
    if (runNian(i)) {
        days += 366;
    }
    else {
        days += 365;
    }
}


//1月 - 4月全月一共有多少天
for (var k = 1; k < month; k++) {
    switch (k) {
        case 1:
            days += 31;
            break;
        case 2:
            if (runNian(year)){
                days += 29;
            }else{
                days += 28;
            }
            break;
        case 3:
            days += 31;
            break;
        case 4:
            days += 30;
            break;
        case 5:
            days += 31;
            break;
        case 6:
            days += 30;
            break;
        case 7:
            days += 31;
            break;
        case 8:
            days += 31;
            break;
        case 9:
            days += 30;
            break;
        case 10:
            days += 31;
            break;
        case 11:
            days += 30;
            break;
        case 12:
            days += 31;
            break;
    }
}



//因为1980年的1月1日前面有两个空位所以加2
days+=2;
console.log(days);


//算出起始位置
var start=days%7;
console.log(start);


//选上这个标签
var day=document.querySelector("#day");


//上一个月一共有多少天
var prevDay=0;
//找到上一个月多少天
switch (month - 1){
	case 1:
            prevDay += 31;
            break;
        case 2:
            if (runNian(year)){
                prevDay+=29;
            }else{
                prevDay+=28;
            }
            break;
        case 3:
            prevDay += 31;
            break;
        case 4:
            prevDay += 30;
            break;
        case 5:
            prevDay += 31;
            break;
        case 6:
            prevDay += 30;
            break;
        case 7:
            prevDay += 31;
            break;
        case 8:
            prevDay += 31;
            break;
        case 9:
            prevDay += 30;
            break;
        case 10:
            prevDay += 31;
            break;
        case 11:
            prevDay += 30;
            break;
        case 12:
            prevDay += 31;
            break;
}


//本月一共有多少天
var thisDay=0;
//找到上一个月多少天
switch (month){
	case 1:
            thisDay += 31;
            break;
        case 2:
            if (runNian(year)){
                thisDay+=29;
            }else{
                thisDay+=28;
            }
            break;
        case 3:
            thisDay += 31;
            break;
        case 4:
            thisDay += 30;
            break;
        case 5:
            thisDay += 31;
            break;
        case 6:
            thisDay += 30;
            break;
        case 7:
            thisDay += 31;
            break;
        case 8:
            thisDay += 31;
            break;
        case 9:
            thisDay += 30;
            break;
        case 10:
            thisDay += 31;
            break;
        case 11:
            thisDay += 30;
            break;
        case 12:
            thisDay += 31;
            break;
}



for (var j=prevDay-start+1; j<=prevDay;j++){
	day.innerHTML+='<span class="h">'+j+'</span>';
}


//取到今天
var d=new Date().getDate();

for (var s=1;s<=thisDay;s++){
	if (s==d) {
		day.innerHTML+='<span class="today">'+s+'</span>';
	}else{
		day.innerHTML+='<span>'+s+'</span>';
	}
}


//总空位是42位
var num=42;

//算出还剩几个位置
var endDay = num -start - thisDay;

for (var e=1;e<=endDay;e++){
	day.innerHTML+='<span class="h">'+e+'</span>';
}


//赋值标题的年和月
document.querySelector("#nian").innerHTML=year;
document.querySelector("#yue").innerHTML=month;
